include/linux/linkage.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_LINKAGE_H
   3 #define _LINUX_LINKAGE_H
   4
   5 #include <linux/compiler_types.h>
   6 #include <linux/stringify.h>
   7 #include <linux/export.h>
   8 #include <asm/linkage.h>
   9
  10 /* Some toolchains use other characters (e.g. '`') to mark new line in macro */
  11 #ifndef ASM_NL
  12 #define ASM_NL           ;
  13 #endif
  14
  15 #ifdef __cplusplus
  16 #define CPP_ASMLINKAGE extern "C"
  17 #else
  18 #define CPP_ASMLINKAGE
  19 #endif
  20
  21 #ifndef asmlinkage
  22 #define asmlinkage CPP_ASMLINKAGE
  23 #endif
  24
  25 #ifndef cond_syscall
  26 #define cond_syscall(x) asm(                            \
  27         ".weak " __stringify(x) "\n\t"                  \
  28         ".set  " __stringify(x) ","                     \
  29                  __stringify(sys_ni_syscall))
  30 #endif
  31
  32 #ifndef SYSCALL_ALIAS
  33 #define SYSCALL_ALIAS(alias, name) asm(                 \
  34         ".globl " __stringify(alias) "\n\t"             \
  35         ".set   " __stringify(alias) ","                \
  36                   __stringify(name))
  37 #endif
  38
  39 #define __page_aligned_data     __section(".data..page_aligned") __aligned(PAGE_SIZE)
  40 #define __page_aligned_bss      __section(".bss..page_aligned") __aligned(PAGE_SIZE)
  41
  42 /*
  43  * For assembly routines.
  44  *
  45  * Note when using these that you must specify the appropriate
  46  * alignment directives yourself
  47  */
  48 #define __PAGE_ALIGNED_DATA     .section ".data..page_aligned", "aw"
  49 #define __PAGE_ALIGNED_BSS      .section ".bss..page_aligned", "aw"
  50
  51 /*
  52  * This is used by architectures to keep arguments on the stack
  53  * untouched by the compiler by keeping them live until the end.
  54  * The argument stack may be owned by the assembly-language
  55  * caller, not the callee, and gcc doesn't always understand
  56  * that.
  57  *
  58  * We have the return value, and a maximum of six arguments.
  59  *
  60  * This should always be followed by a "return ret" for the
  61  * protection to work (ie no more work that the compiler might
  62  * end up needing stack temporaries for).
  63  */
  64 /* Assembly files may be compiled with -traditional .. */
  65 #ifndef __ASSEMBLY__
  66 #ifndef asmlinkage_protect
  67 # define asmlinkage_protect(n, ret, args...)    do { } while (0)
  68 #endif
  69 #endif
  70
  71 #ifndef __ALIGN
  72 #define __ALIGN                 .balign CONFIG_FUNCTION_ALIGNMENT
  73 #define __ALIGN_STR             __stringify(__ALIGN)
  74 #endif
  75
  76 #ifdef __ASSEMBLY__
  77
  78 /* SYM_T_FUNC -- type used by assembler to mark functions */
  79 #ifndef SYM_T_FUNC
  80 #define SYM_T_FUNC                              STT_FUNC
  81 #endif
  82
  83 /* SYM_T_OBJECT -- type used by assembler to mark data */
  84 #ifndef SYM_T_OBJECT
  85 #define SYM_T_OBJECT                            STT_OBJECT
  86 #endif
  87
  88 /* SYM_T_NONE -- type used by assembler to mark entries of unknown type */
  89 #ifndef SYM_T_NONE
  90 #define SYM_T_NONE                              STT_NOTYPE
  91 #endif
  92
  93 /* SYM_A_* -- align the symbol? */
  94 #define SYM_A_ALIGN                             ALIGN
  95 #define SYM_A_NONE                              /* nothing */
  96
  97 /* SYM_L_* -- linkage of symbols */
  98 #define SYM_L_GLOBAL(name)                      .globl name
  99 #define SYM_L_WEAK(name)                        .weak name
 100 #define SYM_L_LOCAL(name)                       /* nothing */
 101
 102 #ifndef LINKER_SCRIPT
 103 #define ALIGN __ALIGN
 104 #define ALIGN_STR __ALIGN_STR
 105
 106 /* === DEPRECATED annotations === */
 107
 108 #ifndef CONFIG_ARCH_USE_SYM_ANNOTATIONS
 109 #ifndef GLOBAL
 110 /* deprecated, use SYM_DATA*, SYM_ENTRY, or similar */
 111 #define GLOBAL(name) \
 112         .globl name ASM_NL \
 113         name:
 114 #endif
 115
 116 #ifndef ENTRY
 117 /* deprecated, use SYM_FUNC_START */
 118 #define ENTRY(name) \
 119         SYM_FUNC_START(name)
 120 #endif
 121 #endif /* CONFIG_ARCH_USE_SYM_ANNOTATIONS */
 122 #endif /* LINKER_SCRIPT */
 123
 124 #ifndef CONFIG_ARCH_USE_SYM_ANNOTATIONS
 125 #ifndef WEAK
 126 /* deprecated, use SYM_FUNC_START_WEAK* */
 127 #define WEAK(name)         \
 128         SYM_FUNC_START_WEAK(name)
 129 #endif
 130
 131 #ifndef END
 132 /* deprecated, use SYM_FUNC_END, SYM_DATA_END, or SYM_END */
 133 #define END(name) \
 134         .size name, .-name
 135 #endif
 136
 137 /* If symbol 'name' is treated as a subroutine (gets called, and returns)
 138  * then please use ENDPROC to mark 'name' as STT_FUNC for the benefit of
 139  * static analysis tools such as stack depth analyzer.
 140  */
 141 #ifndef ENDPROC
 142 /* deprecated, use SYM_FUNC_END */
 143 #define ENDPROC(name) \
 144         SYM_FUNC_END(name)
 145 #endif
 146 #endif /* CONFIG_ARCH_USE_SYM_ANNOTATIONS */
 147
 148 /* === generic annotations === */
 149
 150 /* SYM_ENTRY -- use only if you have to for non-paired symbols */
 151 #ifndef SYM_ENTRY
 152 #define SYM_ENTRY(name, linkage, align...)              \
 153         linkage(name) ASM_NL                            \
 154         align ASM_NL                                    \
 155         name:
 156 #endif
 157
 158 /* SYM_START -- use only if you have to */
 159 #ifndef SYM_START
 160 #define SYM_START(name, linkage, align...)              \
 161         SYM_ENTRY(name, linkage, align)
 162 #endif
 163
 164 /* SYM_END -- use only if you have to */
 165 #ifndef SYM_END
 166 #define SYM_END(name, sym_type)                         \
 167         .type name sym_type ASM_NL                      \
 168         .set .L__sym_size_##name, .-name ASM_NL         \
 169         .size name, .L__sym_size_##name
 170 #endif
 171
 172 /* SYM_ALIAS -- use only if you have to */
 173 #ifndef SYM_ALIAS
 174 #define SYM_ALIAS(alias, name, linkage)                 \
 175         linkage(alias) ASM_NL                           \
 176         .set alias, name ASM_NL
 177 #endif
 178
 179 /* === code annotations === */
 180
 181 /*
 182  * FUNC -- C-like functions (proper stack frame etc.)
 183  * CODE -- non-C code (e.g. irq handlers with different, special stack etc.)
 184  *
 185  * Objtool validates stack for FUNC, but not for CODE.
 186  * Objtool generates debug info for both FUNC & CODE, but needs special
 187  * annotations for each CODE's start (to describe the actual stack frame).
 188  *
 189  * Objtool requires that all code must be contained in an ELF symbol. Symbol
 190  * names that have a  .L prefix do not emit symbol table entries. .L
 191  * prefixed symbols can be used within a code region, but should be avoided for
 192  * denoting a range of code via ``SYM_*_START/END`` annotations.
 193  *
 194  * ALIAS -- does not generate debug info -- the aliased function will
 195  */
 196
 197 /* SYM_INNER_LABEL_ALIGN -- only for labels in the middle of code */
 198 #ifndef SYM_INNER_LABEL_ALIGN
 199 #define SYM_INNER_LABEL_ALIGN(name, linkage)    \
 200         .type name SYM_T_NONE ASM_NL                    \
 201         SYM_ENTRY(name, linkage, SYM_A_ALIGN)
 202 #endif
 203
 204 /* SYM_INNER_LABEL -- only for labels in the middle of code */
 205 #ifndef SYM_INNER_LABEL
 206 #define SYM_INNER_LABEL(name, linkage)          \
 207         .type name SYM_T_NONE ASM_NL                    \
 208         SYM_ENTRY(name, linkage, SYM_A_NONE)
 209 #endif
 210
 211 /* SYM_FUNC_START -- use for global functions */
 212 #ifndef SYM_FUNC_START
 213 #define SYM_FUNC_START(name)                            \
 214         SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)
 215 #endif
 216
 217 /* SYM_FUNC_START_NOALIGN -- use for global functions, w/o alignment */
 218 #ifndef SYM_FUNC_START_NOALIGN
 219 #define SYM_FUNC_START_NOALIGN(name)                    \
 220         SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE)
 221 #endif
 222
 223 /* SYM_FUNC_START_LOCAL -- use for local functions */
 224 #ifndef SYM_FUNC_START_LOCAL
 225 #define SYM_FUNC_START_LOCAL(name)                      \
 226         SYM_START(name, SYM_L_LOCAL, SYM_A_ALIGN)
 227 #endif
 228
 229 /* SYM_FUNC_START_LOCAL_NOALIGN -- use for local functions, w/o alignment */
 230 #ifndef SYM_FUNC_START_LOCAL_NOALIGN
 231 #define SYM_FUNC_START_LOCAL_NOALIGN(name)              \
 232         SYM_START(name, SYM_L_LOCAL, SYM_A_NONE)
 233 #endif
 234
 235 /* SYM_FUNC_START_WEAK -- use for weak functions */
 236 #ifndef SYM_FUNC_START_WEAK
 237 #define SYM_FUNC_START_WEAK(name)                       \
 238         SYM_START(name, SYM_L_WEAK, SYM_A_ALIGN)
 239 #endif
 240
 241 /* SYM_FUNC_START_WEAK_NOALIGN -- use for weak functions, w/o alignment */
 242 #ifndef SYM_FUNC_START_WEAK_NOALIGN
 243 #define SYM_FUNC_START_WEAK_NOALIGN(name)               \
 244         SYM_START(name, SYM_L_WEAK, SYM_A_NONE)
 245 #endif
 246
 247 /*
 248  * SYM_FUNC_END -- the end of SYM_FUNC_START_LOCAL, SYM_FUNC_START,
 249  * SYM_FUNC_START_WEAK, ...
 250  */
 251 #ifndef SYM_FUNC_END
 252 #define SYM_FUNC_END(name)                              \
 253         SYM_END(name, SYM_T_FUNC)
 254 #endif
 255
 256 /*
 257  * SYM_FUNC_ALIAS -- define a global alias for an existing function
 258  */
 259 #ifndef SYM_FUNC_ALIAS
 260 #define SYM_FUNC_ALIAS(alias, name)                                     \
 261         SYM_ALIAS(alias, name, SYM_L_GLOBAL)
 262 #endif
 263
 264 /*
 265  * SYM_FUNC_ALIAS_LOCAL -- define a local alias for an existing function
 266  */
 267 #ifndef SYM_FUNC_ALIAS_LOCAL
 268 #define SYM_FUNC_ALIAS_LOCAL(alias, name)                               \
 269         SYM_ALIAS(alias, name, SYM_L_LOCAL)
 270 #endif
 271
 272 /*
 273  * SYM_FUNC_ALIAS_WEAK -- define a weak global alias for an existing function
 274  */
 275 #ifndef SYM_FUNC_ALIAS_WEAK
 276 #define SYM_FUNC_ALIAS_WEAK(alias, name)                                \
 277         SYM_ALIAS(alias, name, SYM_L_WEAK)
 278 #endif
 279
 280 /* SYM_CODE_START -- use for non-C (special) functions */
 281 #ifndef SYM_CODE_START
 282 #define SYM_CODE_START(name)                            \
 283         SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)
 284 #endif
 285
 286 /* SYM_CODE_START_NOALIGN -- use for non-C (special) functions, w/o alignment */
 287 #ifndef SYM_CODE_START_NOALIGN
 288 #define SYM_CODE_START_NOALIGN(name)                    \
 289         SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE)
 290 #endif
 291
 292 /* SYM_CODE_START_LOCAL -- use for local non-C (special) functions */
 293 #ifndef SYM_CODE_START_LOCAL
 294 #define SYM_CODE_START_LOCAL(name)                      \
 295         SYM_START(name, SYM_L_LOCAL, SYM_A_ALIGN)
 296 #endif
 297
 298 /*
 299  * SYM_CODE_START_LOCAL_NOALIGN -- use for local non-C (special) functions,
 300  * w/o alignment
 301  */
 302 #ifndef SYM_CODE_START_LOCAL_NOALIGN
 303 #define SYM_CODE_START_LOCAL_NOALIGN(name)              \
 304         SYM_START(name, SYM_L_LOCAL, SYM_A_NONE)
 305 #endif
 306
 307 /* SYM_CODE_END -- the end of SYM_CODE_START_LOCAL, SYM_CODE_START, ... */
 308 #ifndef SYM_CODE_END
 309 #define SYM_CODE_END(name)                              \
 310         SYM_END(name, SYM_T_NONE)
 311 #endif
 312
 313 /* === data annotations === */
 314
 315 /* SYM_DATA_START -- global data symbol */
 316 #ifndef SYM_DATA_START
 317 #define SYM_DATA_START(name)                            \
 318         SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE)
 319 #endif
 320
 321 /* SYM_DATA_START -- local data symbol */
 322 #ifndef SYM_DATA_START_LOCAL
 323 #define SYM_DATA_START_LOCAL(name)                      \
 324         SYM_START(name, SYM_L_LOCAL, SYM_A_NONE)
 325 #endif
 326
 327 /* SYM_DATA_END -- the end of SYM_DATA_START symbol */
 328 #ifndef SYM_DATA_END
 329 #define SYM_DATA_END(name)                              \
 330         SYM_END(name, SYM_T_OBJECT)
 331 #endif
 332
 333 /* SYM_DATA_END_LABEL -- the labeled end of SYM_DATA_START symbol */
 334 #ifndef SYM_DATA_END_LABEL
 335 #define SYM_DATA_END_LABEL(name, linkage, label)        \
 336         linkage(label) ASM_NL                           \
 337         .type label SYM_T_OBJECT ASM_NL                 \
 338         label:                                          \
 339         SYM_END(name, SYM_T_OBJECT)
 340 #endif
 341
 342 /* SYM_DATA -- start+end wrapper around simple global data */
 343 #ifndef SYM_DATA
 344 #define SYM_DATA(name, data...)                         \
 345         SYM_DATA_START(name) ASM_NL                             \
 346         data ASM_NL                                             \
 347         SYM_DATA_END(name)
 348 #endif
 349
 350 /* SYM_DATA_LOCAL -- start+end wrapper around simple local data */
 351 #ifndef SYM_DATA_LOCAL
 352 #define SYM_DATA_LOCAL(name, data...)                   \
 353         SYM_DATA_START_LOCAL(name) ASM_NL                       \
 354         data ASM_NL                                             \
 355         SYM_DATA_END(name)
 356 #endif
 357
 358 #endif /* __ASSEMBLY__ */
 359
 360 #endif /* _LINUX_LINKAGE_H */